Metal particles in the nanometer size range (e.g., 1 to 100 nanometers or 1 to 10 nanometers) are of increasing interest in a variety of applications such as catalysis, electronic devices, and sensors. Many of the methods used to prepare metal particles in this size range, however, are problematic.
Particles such as noble metal particles in the nanometer size range have been prepared by reacting soluble metal-containing precursors with a reducing agent such as sodium borohydride in the presence of an alkylthiol capping agent. While this method is effective for producing particles in the nanometer size range, the particle surfaces are usually passivated (i.e., surface functionalized). A passivated noble metal tends to be less effective than non-passivated noble metals in applications such as catalysis or sensing.
Metal particles in the nanometer size range have been prepared within dendritic structures. The dendritic structures have been loaded with cations from a soluble metal salt or acid and then reduced to produce metal particles. These metals are typically coordinated on the outer surface by functional groups within the dendritic structure. Such coordination can disadvantageously affect the utility of the metal particles for various applications such as catalysis or sensing.